Double Wall Research Articles

Dynamic Time Analysis of the Composite Shear Wall on the Grid-tube-type Double Steel Plate Wall with Infilled Concrete

In this paper, based on a 30-story building with frame-core tube structure system, three comparative schemes are established of reinforced concrete core tube construction, steel-reinforced concrete core tube construction and the combined shear wall core tube structure with the grid-tube-type double steel plate wall with infilled concrete are established, and the dynamic elastoplastic time history is analyzed. Research shows that under the influence of a severe earthquake, the lateral strength degradation and stiffness degradation are slow on the Joint structural system of concrete filled steel tubular frame and composite shear wall core tube structure with the grid-tube-type double steel plate wall with infilled concrete, so interlayer shear force and bottom shear force increase, structural lateral stiffness increased significantly, interlayer displacement angle reduces significantly, and it improves the seismic performance of tall building.

Development Research of the Double “L” Shaped Steel Plate-Concrete Composite Shear Wall

A double steel plates composite shear wall member composed of “L” elements (D-L-SCW) was proposed in this paper and its seismic behavior was preliminarily studied. With the shear-span ratio as test parameter, two specimens with actual ratio of 0.5 were constructed and tested in horizontal low-cycle reverse loading test. The failure modes, hysteretic behavior, skeleton curve, ductility and energy dissipation of the specimens were studied. Results showed that the suggested composite shear wall has significant seismic performance and can make more full use of the properties of both materials. The shear-span ratio mainly affected the peak load of the specimens, whilst it didn’t affect the overall deformation trend.

Anatomical, physical, and mechanical parameters of clone plantation tree, Cunninghamia lanceolata

Anatomical characteristics of the plantation tree, Cunninghamia lanceolata were studied. Clonal variability and intra-tree variation, as well as its possibilities of application to the wood industry were analyzed for four clones. Tracheid length from the first to 17th annual ring within clones increased rapidly at first, and then plateaued. The maximum value appeared at the 14th annual ring of clone IV (3795 μm), and the minimum value appeared at the 1st annual ring of clone I (849 μm). Tracheid width and tracheid double wall thickness increased first and then tended to be flat or slightly decreased; tracheid length to width ratio showed an overall increasing trend; the variation of tracheid double wall thickness was not significant. Between clones, the variation coefficient of tracheid width, double wall thickness, and wall to cavity ratio were large. The tissue proportion within clones from large to small was the following: tracheid proportion > wood ray proportion > parenchyma proportion, and there was no significant difference between clones. The basic density within clones showed a gradual increase but a certain fluctuation; the difference between clones was not significant. The maximum crystallinity appeared in clone II (sapwood 55.1%, heartwood 51.2%), and the difference between clones was not significant.

On heat transfer and flow characteristics of jets impinging onto concave surface with varying bleeding arrangements

Purpose The purpose of this study is to investigate the effects of film holes’ arrangements and jet Reynolds number on flow structure and heat transfer characteristics of jet impingement conjugated with film cooling in a semicylinder double wall channel. Design/methodology/approach Numerical simulations are used in this research. Streamlines on different sections, skin-friction lines, velocity, wall shear stress and turbulent kinetic energy contours near the concave target wall and vortices in the double channel are presented. Local Nusselt number contours and surface averaged Nusselt numbers are also obtained. Topology analysis is applied to further understand the fluid flow and is used in analyzing the heat transfer characteristics. Findings It is found that the arrangement of side films positioned far from the center jets helps to enhance the flow disturbance and heat transfer behind the film holes. The heat transfer uniformity for the case of 55° films arrangement angle is most improved and the thermal performance is the highest in this study. Originality/value The film holes’ arrangements effects on fluid flow and heat transfer in an impingement cooled concave channel are conducted. The flow structures in the channel and flow characteristics near target by topology pictures are first obtained for the confined film cooled impingement cases. The heat transfer distributions are analyzed with the flow characteristics. The highest heat transfer uniformity and thermal performance situation is obtained in present work.

Strategy for D-shape assembly of ITER vacuum vessel sector #06 as applying 3D metrology

The first sector of the ITER vacuum vessel (VV) has been delivered to the ITER Organization. One of the critical manufacturing steps is d-shape assembly. The manufactured four poloidal segments (PS 1, 2, 3, 4) are assembled, and then form the d-shape structure with a height of 11.4 m. Each PS is a complex and heavy double-wall structure with an inner shell and outer shell, poloidal and toroidal ribs, and in-wall shielding blocks are filled inside of the double wall as radiation shield. Thus, it is quite difficult to handle for assembly in keeping with the segment final dimensional status, so that it is necessary to set a practical plan. Before conducting actual assembly, the d-shape is virtually fitted using all results of final 3D metrology on each PS. In detail, each inner shell as-built result on four interfaces, plus a margin for welding shrinkage and gap for welding are considered to set the d-shape fit-up reference. To set each PS in the right position as comparing the fit-up reference, the fiducial posts (FPs) on each PS are measured using a 3D metrology system. After done the fit-up on the assembly plate, whole FPs (55 ea.) are checked as verification. As a result, the PS2 and PS4 are shifted Avg 7.4 mm and Avg 7 mm to the poloidal way, respectively. After finished inner shell welding, the whole FPs are also measured. The PS2 and PS4 are still shifted Avg 1.4 mm and Avg 0.8 mm to poloidal way, respectively. Eventually, the as-built dimension on the important part is evaluated with given tolerance as a preliminary prediction of the final d-shape result.

Cooling Energy Use Reduction in Residential Buildings in Egypt Accounting for Global Warming Effects

Residential and commercial buildings are responsible for almost 50% of the total electricity consumption in Egypt. This percentage is expected to increase due to the global warming effect. This work deals with the cooling energy use reduction strategies for residential buildings compatible with the Egyptian market accounting for the global warming effects. A study in the Egyptian market was done to explore the best available technologies in the Egyptian market. A series of dynamic simulations were executed in each city to optimize the building envelope using the best available technologies to reduce the cooling needs. Financial, energetic and environmental factors were taken into consideration, and comparative analysis was done to assess the best alternatives. The double wall with air gap and insulation on the outside was found to be the best alternative in all the cities. Moreover, simple measures to further reduce the cooling energy need were explored, such as the usage of more efficient lighting and night ventilation. This work led to an average reduction of 40% in the cooling energy needs and CO2 emissions across the three cities, with a maximum discounted payback period down to 6.3 years. Future weather files adapted to climate change were generated, and the selected passive strategies were tested to assess the validity of such strategies in the future. The cooling energy needs are expected to increase by 39%, while the peak cooling loads are also expected to increase by 23% by 2080, rendering the current installed HVAC systems undersized.

PC 특수전단벽으로서 더블월의 구조성능 및 내진성능 평가

본 연구는 특수전단벽으로 사용할 수 있는 PC 구조 벽체를 개발하는 것을 목적으로 하였다. 현장타설 공법에 의한 특수전단벽의 난이도 높은 시공성을 개선하기 위하여 더블월의 단부에 용접된 폐쇄형 후프 철근을 배근하여 제작한 PC 특수전단 더블월을 제안하였다. 실험연구를 위하여 3개의 특수전단 DW 실험체(DW)와 비교를 위한 2개의 특수전단 현장타설 실험체(RW)를 대상으로 한 구조실험을 계획하였다. 벽두께(200 mm와 250 mm)와 수평접합부 보강철근의 배치 방법(분산 및 집중)을 변수로 반복가력 횡력실험을 실시하고, RW와 DW의 균열분포와 함께 실험체 강도 및 연성 정도 등을 비교 분석하였다. DW의 내진성능은 FEMA 450의 PC 특수전단벽 내진성능 요구조건에 따라 공칭강도 대비 최대강도, 한계변위각에서의 보유 강도, 원점 부근 강성, 상대적 에너지 소산 정도 등을 평가하였다. 또한 성능기반 평가법(ASCE/SEI 41, ACI 374)에 따라 비선형 모델 특성과 성능수준도 평가하였다. 이상과 같은 분석결과를 토대로 특수전단 DW는 특수전단 RW 이상의 구조성능을 보이면서 PC 구조의 장점을 이용할 수 있는 구조 벽체가 될 수 있다는 결과를 얻었다.

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

Double wall transpiration cooling (DWTC) systems allow the operating temperature of gas turbines to be increased beyond current levels, promising further enhancements in engine efficiency and a reduction in fuel consumption and emissions. Alongside the outstanding cooling performance of DWTC systems, there are structural integrity implications that need to be evaluated. Our theoretical and Finite Element (FE) analysis here determine thermal stresses arising in a range of double wall configurations in two-dimensional (2D) and three-dimensional (3D) space. The 3D geometric effects of wall spacing, wall thickness ratio, connecting pedestal spacing between the walls and pedestal thickness are interpreted based on considerations on 2D idealisations. We highlight that although an inner cool wall may be essential for applying internal impingement cooling in the system to enhance its aerothermal performance, at the same time the inner wall increases compression in the hot outer wall, due to the kinematic constraint that the two walls must extend equally. As a result, the critical compressive stresses in the hot wall can be relieved by using a thinner inner wall. Our study determines the essential nominal stress fields that drive stress concentrations and associated local creep-plasticity-fatigue at critical features in DWTC systems, such as effusion holes and pedestals.

Advances in Additive Manufacturing of fusion materials

Recent analysis result in significant impact on the design of the Helium Cooled Pebble Bed (HCPB) Breeding Blanket (BB). Especially the main demanding sub-component of the BB in terms of fabrication, the First Wall (FW) is highly affected. As a matter of fact, the relevance of the developments made for the industrial fabrication of the FW used e.g. in the EU HCPB Test Blanket Module (TBM) for ITER is limited: On one hand in terms of the overall dimensions, but also in terms of geometry and cooling channel configuration. Thus, a fabrication strategy for the FW was proposed as an option in 2018 based on Additive Manufacturing (AM) offering a solution to cover the new aspects. The dedicated fabrication routine is based on Cold Spray (CS) in alternation with machining. In terms of manufacturing of non-plasma facing complex shaped thin- or double wall BB structures (e.g. Fuel Pins proposed for the HCPB BB) the use of AM also provides benefits compared to conventional technologies. Therefore, the AM process of Selective Laser Melting (SLM) is also investigated in terms of applicability for BBs. This paper gives an overview about the advances in different AM options applied for nuclear fusion structural low activation steels. Possibilities for spin-offs to other technological fields are discussed and conclusions are drawn reflecting licensing aspects and technological limits.

Experimental seismic behavior of double skin composite wall with steel truss

This paper describes an experimental study to investigate the seismic behavior of double skin composite walls (DSCWs) with steel truss. Based on the results of seven specimens tested at full-scale, the influence of aspect ratio, axial compression ratio, and truss spacing to thickness ratio on the seismic behavior of DSCW with steel truss are considered. The failure mode, load-displacement relationship, strength, ductility, stiffness, energy dissipation capacity, and shear deformation were analyzed. The results showed that the aspect ratio had the most significant influence on the failure mode and seismic behavior of the specimen. For specimens with an aspect ratio of 2.0, shear compression failure dominates, while for specimens with an aspect ratio over 2.0, flexure shear failure dominates. The strength and initial stiffness decreased with the increase of aspect ratio, but the ductility and energy dissipation became better with the increase of aspect ratio. The axial compression had a little positive effect on the strength, but the specimen with a smaller axial compression ratio had better ductility and energy dissipation. The large truss spacing to thickness ratio weakened the external restraint effect of the steel truss on the steel plates, leading to premature buckling and failure of the specimen.

Compressive behaviour of double skin composite shear walls stiffened with steel-bars trusses

This research investigates the compressive behaviour of double skin composite (DSC) shear walls stiffened with steel-bars trusses. Eight specimens were fabricated and tested. The test focused on the parameters including, the welding spot spacing-to-thickness ratio (b/t) of the steel plate and plate slits. The reinforced concrete (RC) shear walls were also tested as comparative specimens. The experimental results indicate that the decrease in the welding spot spacing-to-thickness ratio or the steel plate with slits can improve the buckling capacity of the DSC shear wall. The maximum capacity of DSC shear wall stiffened with steel-bars trusses is larger than that of the RC shear wall. Meanwhile, the finite element model (FEM) is established and validated in comparison with the experimental results. The parameters, including the welding spot spacing-to-thickness ratio, shape factor (the horizontal spacing of welding spot-to-the vertical spacing ratio, namely b/a), initial geometric imperfection coefficient (β) and material strength, are analyzed. The buckling capacity and maximum capacity of the DSC shear wall are enhanced by decreasing the shape factor or the initial geometric imperfection coefficient or increasing the material strength. The formulas are put forward to calculate the buckling capacity and maximum capacity of DSC shear wall, whose results correspond well to the tested and simulated ones.

Anodic TiO2 nanotube walls reconstructed: Inner wall replaced by ALD TiO2 coating

A reconstruction process of TiO2 nanotube (TNT) layers towards their superior photoelectrochemical performance and photocatalytic activity is presented. At first, TNT layers (~5 μm thick, ~250 nm in diameter) were prepared via electrochemical anodization to obtain double-wall (DW) TNT layers. Second, a selective chemical treatment was conducted to etch the inner wall, yielding single-wall (SW) TNT layers. Third, TNT layers were coated by an additional approx. 5.5 nm, 11 nm, and 16 nm thick TiO2 coatings, respectively, using Atomic Layer Deposition (ALD). A pronounced increase in the incident photon-to-electron conversion efficiency (reaching ~85% at λ = 350 nm) was achieved on SW TNT layers coated with 11 nm thick ALD coatings compared to SW without coating (~35% at λ = 350 nm). This is due to the optimal thickness of the ALD TiO2 coating that passivates surface states and improves the separation of the photogenerated charge carriers. Photocatalytic performance of SW TNT layers with 11 nm thick ALD coatings (rate constant; k = 0.1156 min−1) was increased by approx. 10-times compared to that of the nowadays most reported blank DW TNT layers (rate constant; k = 0.0119 min−1).

Sound insulation of gypsum block partitions: An analysis of single and double walls

This paper presents an evaluation regarding the sound insulation of simple walls built with gypsum blocks, both solid and hollow, with different thicknesses and densities, and double walls with and without acoustic absorbent material. Currently, the sound reduction index (R) is one of the parameters used in residential building projects in Brazil, since it is of fundamental importance for predicting acoustic insulation in the field, a requirement recommended by the Brazilian performance standard ABNT NBR 15575 [1], in line with international standards. Gypsum blocks are elements commonly used in the internal vertical partitions of buildings, in Europe and especially in Brazil. In this paper, the sound reduction index of 22 partitions was analyzed by conducting tests in a standardized laboratory. The results show that, above 70 kg/m2, hollow gypsum blocks tend to demonstrate greater acoustic efficiency than solid blocks. The critical frequency of the single walls was analyzed; these values theoretically calculated for the solid gypsum blocks are within the frequency range obtained experimentally. The double walls without acoustic absorbent material showed similar efficiency, regardless of the air gap. Double walls with acoustic absorbent material are more efficient and this varies depending on what materials, such as glass wool and PET wool, are placed in the same space between the walls. It is still very rare for the literature to report laboratory data regarding the acoustic performance of the gypsum blocks used in this paper and therefore our doing so is a significant contribution to this field of study.

New-age facades-Double Skin Architecture

A modern building system consisting of two skins is the double-skin facade. The double wall allows the air to flow through within the intermediate cavity. The cavity can be ventilated through a fan or mechanical system. The air flow is decided based on the climatic conditions, usage within the building and buildings cooling techniques. The double skin is mostly of glass and the gap can vary from 20cm to 2metres apart. The cavity can be mounted with a solar shadin device for safety and heat extraction purposes.

Rumen Cannulation of the Red Sokoto (Maradi) Goats for Nutritional Studies in Nigeria

TWO techniques for cannulating the rumen of the Red Sokoto goat of Nigeria are described. Stump type cannulae made of rigidblack., vulcathene1 material with screwable corks were found to be more suitable than the flexible cannulae made of plastisol2. They appeared to be well tolerated and remained in situ inspite of the animals’ nervous temperament and somewhat flabby abdominal wall. Experiences with some forty five of such cannulations performed between October 1970 and January 1975 are reported. These showed that although the double abdominal wall incision approach offered a better technique for cannulae implantation into the rumen of goats, strict routine post-operative attention was essential to avoid a range of post cannulation problems, such as pericannulae necrosis and infection, excessive leakage of the rumen liquor and partial or complete rejection of feed by the cannulated animals consequent upon such complications.

Formation mechanism of tearing defects in machining Nomex honeycomb core

Nomex honeycomb core has been widely applied in aerospace industries due to its superior strength and rigidity. However, the machining defects of honeycomb core can deteriorate the bonding strength between honeycomb core and connective face sheet. This paper investigates the tearing defects formatted in milling process of Nomex honeycomb core. Firstly, a cutting force model is proposed to predict the milling forces under various tool entrance angles. Then, finite element simulation for machining honeycomb wall is conducted to reveal the formation mechanism of tearing defects. The accuracy of the model is verified by a group of experiments under different entrance angles and the relative error is below 25% in 1-direction and 20% in 2-direction. It is found that the formation of tearing defects is closely related to the deformation of honeycomb wall and the component of cutting force in direction parallel to wall. The tool entrance angle can be thus optimized based on the reduction of tearing defects. The optimized entrance angle of double wall is among 40° and 70°.

Louver and effusion cooling heat transfer for a double wall effusion plate with impingement jet array coolant supply

Louver slot cooling is employed, which consists of an aligned collection of film cooling holes, contained within a specially-designed device which concentrates, and directs the coolant from a slot, so that cooling air then advects as a layer downstream along the test surface. This louver-supplied coolant is then supplemented by coolant which emerges from different rows of downstream film cooling holes. Coolant for both cooling arrangements is supplied using an array of impingement jets. Experimental data are provided for a mainstream Reynolds number Rems range of 168,000–181,000. Full-coverage film cooling initial blowing ratio values are 2.5, 3.2, 4.4, and 5.2, with respective louver slot blowing ratios of 1.2, 1.5, 2.1, and 2.4. Measured lateral-averaged adiabatic effectiveness results show that, with impingement supply cooling only, for blowing ratios of 4.4 and lower, the louver and effusion cooling arrangement generally provides higher effectiveness, relative to an effusion cooling only arrangement. For all blowing ratios considered, another advantage of the louver slot is more uniform values of increased effectiveness along the entire test surface, including locations which are just downstream of the slot. Relatively weak dependence on blowing ratio is present for the louver and film cooling arrangement, in contrast to the effusion only configuration, where effectiveness data generally increase progressively and substantially (at most x/de locations) as the blowing ratio becomes larger. Lateral-averaged heat transfer coefficient values for the effusion cooling only arrangement, and for the louver and effusion cooling arrangement, are approximately quantitatively similar when the blowing ratio is 4.3 to 4.4. Data for blowing ratios BR of 5.2 to 5.5 show that the louver and effusion cooling gives much lower lateral-averaged heat transfer coefficients, compared to the effusion cooling only arrangement. This is a result of reduced local turbulent thermal transport levels within the wake flows which are present downstream of the louver leap device.

Self-template fabrication of multi-scaled ZnFe2O4 microspheres and their excellent lithium-ion storage properties

Self-template multi-scaled structure of ZnFe2O4 (ZFO) microspheres were synthesized through a solvothermal method, subsequently accompanied by various annealing processes. Specifically, hollow microspheres ZFO samples with modifiable internal structures (ranging from solid, core-in-hollow wall and double wall hollow) were synthesized differently through a mutual cooperation of inward-outward ripening mechanism by an anisotropic heating process during the calcination process. As active anodes for lithium-ion batteries (LIBs), that as-synthesized ZFO electrodes exhibited outstanding electrochemical properties and cyclic stabilities. Importantly, density functionally theoretical calculations have been investigated so as to understand the intermediate structures and electrochemical mechanisms of as-synthesized electrodes in the initial discharge process.

Experimental and Numerical Studies on the Structural Performance of a Double Composite Wall

In this study, experiments and numerical analyses were carried out to examine the flexural and shear performance of a double composite wall (DCW) manufactured using a precast concrete (PC) method. One flexural specimen and three shear specimens were fabricated, and the effect of the bolts used for the assembly of the PC panels on the shear strength of the DCW was investigated. The failure mode, flexural and shear behavior, and composite behavior of the PC panel and cast-in-place (CIP) concrete were analyzed in detail, and the behavioral characteristics of the DCW were clearly identified by comparing the results of tests with those obtained from a non-linear flexural analysis and finite element analysis. Based on the test and analysis results, this study proposed a practical equation for reasonably estimating the shear strength of a DCW section composed of PC, CIP concrete, and bolts utilizing the current code equations.

Eccentric compressive behaviour of double steel-concrete shear wall constrained with ribs and bars

By adding ribs and bars to form the double steel-concrete shear wall constrained with ribs and bars, the steel plate of the whole steel-concrete shear wall can be strengthened of the constraint. The research on Eccentric compressive behavior of double steel-concrete shear wall constrained with rib and bar is less, this paper analyzes double steel plate concrete shear wall by using larger length-width rectangular CFST column research methods. Based on the constitutive relation of the rectangular CFST column with ribs and bars, the relative parameters are changed, and a program is written to compare and analyze eccentric compressive behavior of double steel-concrete shear wall constrained with ribs and bars compared with that double steel plate concrete shear wall only constrained with bars.